(1) Field of the Invention
The present invention relates to an intake system for an internal combustion engine. More particularly, it relates to an intake system for an engine, which can improve combustion efficiency and reduce emission by providing air with high swirl flow into each combustion chamber.
(2) Description of the Prior Art
A particular type of engine has a fuel injection system for inducing only air by negative pressure of an engine and a fuel injector for injecting fuel to a flow of the induced air.
This engine is designed such that the air is induced into an intake chamber called a surge tank and then flows into a combustion chamber.
The intake chamber is connected with a throttle body and supplied with the air required for combustion. The intake chamber provides the air to the plural combustion chambers via an intake manifold.
The intake manifold is connected with an intake port of a cylinder block to supply the air into the combustion chamber. The fuel injector is mounted on the intake port to inject the fuel to the flow of the air flowing to the combustion chamber.
However, since the fuel injector injects the fuel in only one place, that is, an outskirt of an inner circumference of the intake port, the air and fuel are not uniformly mixed.
Further, since air flow induced into the intake port through the intake manifold is generally laminar, the air and the fuel are not uniformly mixed when the fuel is injected to such a flow, and it causes a deterioration of the engine efficiency because of the limit for supplying with the sufficient air.
The mixed gas induced into the combustion chamber generates the power of the engine with ignition by a spark plug and combustion. Thus, if the gas in which the air and the fuel are ununiformly mixed is induced into the combustion chamber, it causes incomplete combustion and a prolongation of ignition time.
Since the incomplete combustion causes a lot of harmful materials (HC, NOx) in exhaust gas and a deterioration of the engine output, it does not improve the fuel consumption ratio.
An intake dispenser having a swirl guide in an intake chamber is disclosed in Japanese Utility Model Publication No. 91-65822 to solve such a problem.
However, the high swirl can not be made though the intake guide provided in the intake dispenser, because this device provides intake gas swirl flow by dividing the intake gas in two directions.
In addition, the method disclosed in Japanese Utility Model Publication No. 85-30322 has a demerit that resistance is applied to the flow of the intake gas though a blade mounted on the lower part of the valve guide guiding the intake valve makes the intake gas be swirl flow.